According to a state health official and University of Texas researchers, Chagas disease, a tropical parasitic disease that can lead to life-threatening heart and digestive disorders, may be more widespread in Texas than previously thought.

The disease that claims thousands of lives in Latin America each year is often transmitted by triatomine insects, also known as “assassin bugs” or "kissing bugs." Central and South Texas are the two highest-risk areas in the state for Chagas, according to Sahotra Sarkar, a professor of integrative biology and philosophy who has been studying the disease for five years.

The insects are infected from biting rodents or other animals with Chagas. They are nocturnal parasites that nest in brush piles, dog houses, rodent nests, chicken coops and cracks in substandard housing. They typically infect humans and animals by biting around the mouth or eyes to suck blood while the new host sleeps, leaving infectious feces behind that gets rubbed into the wound.

Generally, dogs are the only animals that show signs of disease. Chagas disease can also occur when a dog eats feces from an infected host (opossum, raccoon, and armadillo), or through a blood transfusion.

Two forms of Chagas disease are observed in dogs: acute and chronic. Some dogs enter an extended period, from months to years, where no symptoms develop. However, during the asymptomatic period, there is a progressive and insidious development of the parasite, leading to the degeneration and inflammation of the heart, which can eventually cause heart failure and death.

Symptoms include:

Acute (typically dogs younger than 2)
– Diarrhea
– Depression
– Lethargy
– Exercise intolerance
– Walking difficulties
– Rapid body jerks, seizures
– Swollen lymph nodes
– Increased heart rate (tachycardia)
– Congestive heart failure (left and right-sided)

Chronic (typically older dogs)
– Weakness
– Fainting
– Exercise intolerance
– Increased heart rate (tachycardia)

According to the U.S. Centers for Disease Control and Prevention, the bite from a Chagas infected insect can cause an allergic reaction characterized by severe redness, itching, swelling, hives, or, rarely, anaphylactic shock to humans.

Typically, the person recovers after experiencing flu-like symptoms that can include nausea and vomiting, rash and swollen glands. Without treatment, the infection can be lifelong. In 20 to 30 percent of cases, the disease can reappear a decade or two later as difficulty swallowing because of an enlarged esophagus, abdominal pain because of an enlarged colon, or heart disease, including congestive heart failure or sudden cardiac arrest, according to the CDC.

Just seven cases have been confirmed nationally, including four in Texas and one each in California, Tennessee and Louisiana. Simple changes in lifestyle, such as keeping piles of wood away from the home, have been effective. Selective spraying for the insects has also been key to decreasing the risk of the disease.

-- Dr. Bill Craig --